500 WHEELER. 



they were at first confined, is only what might be expected. And that 

 such varieties and subspecies should be much more numerous in the 

 Rocky Mountains than in the Eastern States is also to be expected, 

 when we consider the much greater variety of physical conditions in 

 that region. The high mountains running north and south through 

 many degrees of latitude, with very high timber and snow lines and 

 often broken into isolated ranges separated by arid basins or " parks," 

 sometimes of great extent, constitute a much more favorable territory 

 for the production of endemic races and varieties than the compact 

 east and west massif of the Alps with their low timber and snow lines 

 and narrow valleys. Some very short mountain ranges, especially 

 in Arizona, New Mexico and Western Texas are, in fact, quite insular, 

 being completely surrounded by the desert from which they rise, and 

 like islands have developed numerous endemic, or precinctive forms. 

 This is very clearly seen in the Huachuca Moimtains of Arizona, which 

 are inhabited by several ants and other insects not known to occur in 

 any other localities. The Coast Range and Sierra Cascade Ranges 

 have also each developed a number of endemic forms. Unfortu- 

 nately we are unable at the present time to appreciate the precise 

 character and extent of this endemicity in our western mountains, 

 because our knowledge of the distribution of any single insect group 

 in any one of the various ranges is very fragmentary. This is equally 

 true of the Appalachian System (White Mountains, Adirondacks, 

 mountains of North Carolina and Georgia). Certainly no more inter- 

 esting work could be undertaken by our taxonomic entomologists 

 than a detailed and systematic survey of the various groups of insects 

 in all these ranges after the manner of the fine surveys of the distri- 

 bution of vertebrates and woody plants by Dr. C. H. Merriam and 

 his collaborators. 



